Sift together flour, granulated sugar, baking powder, soda and salt. Add brown sugar, shortening, egg, and vanilla; beat well. Stir in rolled oats and walnuts. Form dough into small balls. Dip tops in a little additional granulated sugar. Place on ungreased cookie sheet. Bake in moderate oven 375 degrees for 10-12 minutes. Makes about 3 1/2 dz. Cookies.